This concept defines the quantized states of electron probability density within atomic nuclei governed by quantum mechanical selection rules and orbital angular momentum constraints. It establishes the theoretical framework where electrons occupy discrete principal energy shells and subshells characterized by specific azimuthal, magnetic, and spin quantum numbers under the Pauli exclusion principle. The theory operates strictly within the domain of Atomic Physics as a foundational mechanism for explaining spectral line structures and chemical reactivity potentials without invoking macroscopic thermodynamic variables.
Prerequisite chain context: requires Structure Of An Atom In Atomic Theory.